阅读说明：本技术 储能铁路功率调节器及其控制方法 (Energy storage railway power regulator and control method thereof ) 是由 胡雪凯 戎士洋 周文 夏彦卫 耿博良 肖国春 于 2021-07-08 设计创作，主要内容包括：本发明适用于电能质量与储能控制技术领域,提供了一种储能铁路功率调节器及其控制方法,该储能铁路功率调节器包括：并联连接的三个桥臂模块；每个桥臂模块包括交流滤波电感以及连接结构相同且相互串联的上桥臂子模块、下桥臂子模块,交流滤波电感的一端连接在上桥臂子模块和下桥臂子模块之间,另一端作为对应桥臂模块的第一端；每个桥臂子模块包括串联连接且数目相同的至少两个变换器单元,各个桥臂子模块中至少一个桥臂子模块的至少两个变换器单元既包含半桥变换器单元又包含储能半桥变换器单元,储能半桥变换器单元由储能单元、半桥变换器和直流稳压电容并联连接构成。本发明的储能铁路功率调节器的拓扑结构和控制方法灵活可靠。(The invention is suitable for the technical field of power quality and energy storage control, and provides an energy storage railway power regulator and a control method thereof, wherein the energy storage railway power regulator comprises: three bridge arm modules connected in parallel; each bridge arm module comprises an alternating current filter inductor, an upper bridge arm submodule and a lower bridge arm submodule which have the same connecting structure and are connected in series, one end of the alternating current filter inductor is connected between the upper bridge arm submodule and the lower bridge arm submodule, and the other end of the alternating current filter inductor is used as the first end of the corresponding bridge arm module; each bridge arm sub-module comprises at least two converter units which are connected in series and have the same number, at least two converter units of at least one bridge arm sub-module in each bridge arm sub-module comprise a half-bridge converter unit and an energy storage half-bridge converter unit, and the energy storage half-bridge converter unit is formed by connecting an energy storage unit, a half-bridge converter and a direct current voltage stabilizing capacitor in parallel. The topological structure and the control method of the energy storage railway power regulator are flexible and reliable.)

1. An energy storage railway power conditioner, comprising: the bridge arm comprises a first bridge arm module, a second bridge arm module and a third bridge arm module which are connected in parallel;

the first end of the first bridge arm module, the first end of the second bridge arm module and the first end of the third bridge arm module are respectively used for connecting a traction power supply network;

each bridge arm module comprises an alternating current filter inductor, an upper bridge arm submodule and a lower bridge arm submodule which have the same connecting structure and are connected in series, one end of the alternating current filter inductor is connected between the upper bridge arm submodule and the lower bridge arm submodule, and the other end of the alternating current filter inductor is used as the first end of the corresponding bridge arm module; each bridge arm sub-module comprises at least two converter units which are connected in series and have the same number, at least two converter units of at least one bridge arm sub-module in each bridge arm sub-module comprise a half-bridge converter unit and an energy storage half-bridge converter unit, and the energy storage half-bridge converter unit is formed by connecting an energy storage unit, a half-bridge converter and a direct current voltage stabilizing capacitor in parallel.

2. The energy-storing railway power conditioner of claim 1, wherein said storage tankA half-bridge capable converter cell comprising: energy storage battery Bat and energy storage battery filter inductor L_bSwitch tube S₅Switch tube S₆Diode D₅Diode D₆Formed energy storage unit, half-bridge converter HB and DC voltage-stabilizing capacitor C₂；

The positive electrode of the energy storage battery Bat and the filter inductor L of the energy storage battery_bIs connected with the switch tube S, the negative pole of the energy storage battery Bat is respectively connected with the switch tube S₆Source electrode of, the diode D₆Positive electrode of (2), the DC voltage-stabilizing capacitor C₂Is connected to a first end of the half-bridge converter HB; a first end of the half-bridge converter HB serves as an input end or an output end of the energy-storing half-bridge converter unit;

the energy storage battery filter inductor L_bIs connected to the switching tube S at the other end₅Source electrode of and the switching tube S₆Between the drain electrodes of (1);

the switch tube S₅And the source of the diode D₅Is connected to the positive pole of the switching tube S₅Respectively with the diode D₅Negative pole of (2), the direct current voltage-stabilizing capacitor C₂Is connected with the third end of the half-bridge converter HB;

the switch tube S₆And the drain electrode of the diode D₆The negative electrode of (1) is connected;

the switch tube S₅And the switching tube S₆The grid of the grid is used for inputting a first control signal;

a second terminal of the half-bridge converter HB serves as an output terminal or an input terminal of the energy-storing half-bridge converter unit.

3. An energy storing railway power conditioner as claimed in claim 1 or 2 wherein the half bridge converter cell comprises: switch tube S₁Switch tube S₂Diode D₁And a diode D₂Formed half-bridge converter and capacitor C₁；

The switch tube S₁And said diode D₁Is connected as the third terminal of the half-bridge converter, the switching tube S₂And said diode D₂The positive electrode of the half-bridge converter is connected to serve as a first end of the half-bridge converter; the switch tube S₁Source electrode of and the switching tube S₂The drain of the half-bridge converter is connected to serve as a second end of the half-bridge converter; the switch tube S₁And the source of the diode D₁The positive electrode of (1) is connected; the switch tube S₂And the drain electrode of the diode D₂The negative electrode of (1) is connected; the first end of the half-bridge converter is used as the input end or the output end of the half-bridge converter unit; the second end of the half-bridge converter is used as the output end or the input end of the half-bridge converter unit;

the capacitor C₁Is connected to a third terminal of the half-bridge converter, the capacitor C₁Is connected to a first terminal of the half-bridge converter;

the switch tube S₁And the switching tube S₂Is used for inputting a second control signal.

4. A control method applied to the energy storage railway power regulator according to any one of claims 1 to 3, wherein all energy storage units in the energy storage railway power regulator form an energy storage system, the control method comprising:

acquiring the operating parameters of the energy storage railway power regulator; the operation parameters comprise each phase load current of the electric locomotive load corresponding to the energy storage railway power regulator, each phase compensation current of the energy storage railway power regulator, first capacitance voltage of each half-bridge converter unit in the energy storage railway power regulator, and second capacitance voltage, actual current of an energy storage battery and actual charge state of the energy storage battery of each energy storage half-bridge converter unit in the energy storage railway power regulator;

carrying out current compensation processing on the load current of each phase, and calculating to obtain a first modulation signal controlled by the alternating current;

performing loop current control processing based on the compensation current of each phase, the first capacitor voltage and the second capacitor voltage, and calculating to obtain a second modulation signal for loop current control;

performing unit capacitor voltage balance control based on the first capacitor voltage, the second capacitor voltage and the actual current of the energy storage battery, performing direct current control based on the actual current of the energy storage battery and the actual charge state of the energy storage battery, and calculating to obtain a third modulation signal of unit control;

and generating a second control signal of the half-bridge converter unit and a first control signal of an energy storage unit in the energy storage half-bridge converter unit according to the first modulation signal, the second modulation signal and the third modulation signal.

5. The control method according to claim 4, wherein the calculating the first modulation signal for controlling the ac current by performing the current compensation process on the load current of each phase includes:

acquiring a first equivalent current, a second equivalent current and a capacitance reference voltage in the energy storage railway power regulator; the first equivalent current is equivalent current of active power output to the alpha phase by the energy storage system through the energy storage railway power regulator at the alternating current side of the energy storage railway power regulator, and the second equivalent current is equivalent current of active power output to the beta phase by the energy storage system through the energy storage railway power regulator at the alternating current side of the energy storage railway power regulator;

carrying out current compensation processing according to the load current of each phase, the first equivalent current and the second equivalent current, and calculating to obtain an initial compensation current d-axis component;

calculating the capacitor reference voltage to obtain a per unit value of the first capacitor total energy reference value of all converter units in the energy storage railway power regulator;

calculating to obtain a per unit value of the total energy of the first capacitors of all converter units in the energy storage railway power regulator according to the first capacitor voltage and the second capacitor voltage;

adjusting the d-axis component of the initial compensation current according to the per-unit value of the first capacitance total energy reference value and the per-unit value of the first capacitance total energy, and calculating to obtain a d-axis component of the compensation current;

carrying out dq conversion on the load current of each phase, and calculating to obtain a q-axis component of the load current;

multiplying the q-axis component of the load current by-1 to obtain a q-axis component of the compensation current;

carrying out dq inverse transformation according to the d-axis component and the q-axis component of the compensation current, and calculating to obtain a reference instruction of the compensation current of each phase;

and calculating to obtain a first modulation signal controlled by the alternating current according to the compensation current of each phase and the compensation current reference instruction of each phase.

6. The control method of claim 5, wherein said obtaining the first equivalent current, the second equivalent current comprises:

acquiring alpha-phase load active power and beta-phase load active power of an electric locomotive load corresponding to the energy storage railway power regulator, the maximum output power of an energy storage system of the energy storage railway power regulator, the allowed maximum charge state of an energy storage battery of each energy storage half-bridge converter unit in the energy storage railway power regulator and the allowed minimum charge state of the energy storage battery;

judging whether the active power of the alpha-phase load, the active power of the beta-phase load and the actual state of charge of the energy storage battery meet preset conditions or not, wherein the preset conditions are that the sum of the active power of the alpha-phase load and the active power of the beta-phase load is greater than zero and the actual state of charge of each energy storage battery is greater than the corresponding allowable minimum state of charge of the energy storage battery, or the sum of the active power of the alpha-phase load and the active power of the beta-phase load is less than zero and the actual state of charge of each energy storage battery is less than the corresponding allowable maximum state of charge of the energy storage battery;

if the alpha-phase load active power, the beta-phase load active power and the actual state of charge of the energy storage battery meet the preset conditions, calculating to obtain an absolute value of the difference between the alpha-phase load active power and the beta-phase load active power, and judging whether the absolute value is less than or equal to the maximum output power of the energy storage system;

if the absolute value is less than or equal to the maximum output power of the energy storage system, the method is based onAcquiring a first equivalent current and a second equivalent current;

if the absolute value is greater than the maximum output power of the energy storage system, the method is based onAcquiring a first equivalent current and a second equivalent current;

if the active power of the alpha-phase load, the active power of the beta-phase load and the actual state of charge of the energy storage battery do not meet the preset conditions, determining that the first equivalent current and the second equivalent current are both zero;

wherein i_αbIs the first equivalent current i_βbFor the second equivalent current, P_bmIs the maximum output power, U, of the energy storage system_sFor the amplitude of the feed line voltage, P_αLFor the alpha-phase load active power, P_βLFor the beta-phase loaded active power, F₁＝sin(ωt-π/6)，F₂Sin (ω t-pi/2), ω is the grid angular frequency, f₁、f₂、f₃Are coefficients.

7. The control method according to any one of claims 4 to 6, wherein calculating a second modulation signal for loop control by performing loop control processing based on the compensation current of each phase, the first capacitance voltage, and the second capacitance voltage includes:

decomposing the compensation current of each phase, and calculating to obtain a circulation reference value of each phase according to a decomposition result;

calculating to obtain a per unit value of the total second capacitance energy of all the converter units in each upper bridge arm sub-module and a per unit value of the total third capacitance energy of all the converter units in each lower bridge arm sub-module according to the first capacitance voltage and the second capacitance voltage;

calculating a per unit value of a total energy reference value of the second capacitor of each bridge arm module according to the obtained capacitor reference voltage;

performing proportional integral adjustment according to the difference between the sum of the per-unit value of the total energy of the second capacitor and the per-unit value of the total energy of the third capacitor and the per-unit value of the reference value of the total energy of the second capacitor, and calculating to obtain a phase equilibrium control power reference value of each phase;

calculating to obtain a phase equalization control signal of each phase according to the phase equalization control power reference value;

performing proportional integral adjustment according to the difference between the per-unit value of the total energy of the second capacitor and the per-unit value of the total energy of the third capacitor, and calculating to obtain a bridge arm balance control power reference value of each phase;

calculating to obtain bridge arm balance control signals of each phase according to the bridge arm balance control power reference value;

and regulating the acquired actual circulation of each phase of the energy storage railway power regulator, the circulation reference value of each phase, the phase balance control signal of each phase and the bridge arm balance control signal of each phase through a proportional-integral resonance regulator, and calculating to obtain a second modulation signal for circulation control.

8. The control method of claim 7, further comprising, before calculating the phase equalization control signal for each phase based on the phase equalization control power reference value:

calculating to obtain a total current of a first energy storage battery of each upper bridge arm submodule, a total current of a second energy storage battery of each lower bridge arm submodule, a total current of a third energy storage battery of each bridge arm module and an average current of the energy storage batteries of the bridge arm modules in the energy storage railway power regulator according to the actual current of the energy storage batteries;

the calculating the phase equalization control signal of each phase according to the phase equalization control power reference value includes:

performing proportional feedforward adjustment according to the difference between the total current of the third energy storage battery and the average current of the energy storage battery, and calculating to obtain a first adjustment result;

correcting the phase equalization control power reference value according to the first adjustment result, and calculating to obtain a phase equalization control signal of each phase according to the corrected phase equalization control power reference value;

the step of calculating to obtain the bridge arm balance control signal of each phase according to the reference value of the bridge arm balance control power comprises the following steps:

performing proportional feedforward adjustment according to the difference between the total current of the first energy storage battery and the total current of the second energy storage battery, and calculating to obtain a second adjustment result;

and correcting the bridge arm balance control power reference value according to the second adjusting result, and calculating to obtain bridge arm balance control signals of each phase according to the corrected bridge arm balance control power reference value.

9. The control method according to any one of claims 4 to 6, wherein the performing cell capacitor voltage equalization control based on the first capacitor voltage, the second capacitor voltage and the actual energy storage battery current, performing direct current control based on the actual energy storage battery current and the actual energy storage battery state of charge, and calculating a third modulation signal for cell control comprises:

obtaining bridge arm current of each bridge arm submodule in the energy storage railway power regulator;

calculating to obtain the average energy storage battery current of the bridge arm of each bridge arm submodule in the energy storage railway power regulator according to the actual current of the energy storage battery;

calculating to obtain the average voltage of the capacitor of each bridge arm submodule in the energy storage railway power regulator according to the first capacitor voltage and the second capacitor voltage;

adjusting according to the first capacitor voltage, the capacitor average voltage, the bridge arm average energy storage battery current and the bridge arm current, and calculating to obtain a first sub-modulation signal of each half-bridge converter unit in the energy storage railway power regulator;

adjusting according to the second capacitor voltage, the actual current of the energy storage battery, the average voltage of the capacitor, the average current of the energy storage battery of the bridge arm and the current of the bridge arm, and calculating to obtain a second sub-modulation signal of each energy storage half-bridge converter unit in the energy storage railway power regulator;

calculating to obtain the average charge state of the energy storage batteries of all energy storage half-bridge converter units in the energy storage railway power regulator according to the actual charge state of the energy storage batteries;

according toCalculating to obtain a first energy storage battery current reference value;

adjusting according to the first energy storage battery current reference value, the energy storage battery actual current, the energy storage battery actual state of charge and the energy storage battery average state of charge, and calculating to obtain a third sub-modulation signal of each energy storage half-bridge converter unit in the energy storage railway power regulator;

taking the first sub-modulation signal, the second sub-modulation signal and the third sub-modulation signal as a third modulation signal for unit control;

wherein the content of the first and second substances,is a first energy storage battery current reference value, I_αbIs the first equivalent current amplitude, I_βbFor the second equivalent current amplitude, U_sIs the amplitude of the feeder voltage, U_batJ is a phase a, b, c, and k is p, N, which represents the upper arm submodule p or the lower arm submodule N, N_jkAnd the total number of energy storage half-bridge converter units included in the k bridge arm sub-modules of the bridge arm module corresponding to j in the energy storage railway power regulator is the total number of the energy storage half-bridge converter units.

10. The control method of claim 9, further comprising, after calculating the first energy storage cell current reference:

according toCalculating to obtain a second energy storage battery current reference value;

wherein the content of the first and second substances,in order to control the energy storage battery current reference value of the z-th energy storage half-bridge converter unit in the k-bridge arm sub-module of the j-corresponding bridge arm module in the energy storage railway power regulator, wherein z is 1,2, … N_jkAnd represents the z & ltth & gt energy storage half bridge converter unit in the k bridge arm sub-module of the j corresponding bridge arm module in the energy storage railway power regulator, k_p5For adjusting the direct proportionality coefficient of the state-of-charge equilibrium speed, SOC_jkzThe actual state of charge, SOC, of the energy storage battery of the energy storage half-bridge converter unit of the z th energy storage half-bridge converter unit in the k bridge arm sub-module of the bridge arm module corresponding to j in the energy storage railway power regulator_avThe average state of charge of the energy storage battery is obtained;

the third sub-modulation signal of each energy storage half-bridge converter unit in the energy storage railway power regulator is obtained through calculation according to the first energy storage battery current reference value, the energy storage battery actual current, the energy storage battery actual state of charge and the energy storage battery average state of charge, and the third sub-modulation signal comprises:

and adjusting according to the second energy storage battery current reference value, the energy storage battery actual current, the energy storage battery actual state of charge and the energy storage battery average state of charge, and calculating to obtain a third sub-modulation signal of each energy storage half-bridge converter unit in the energy storage railway power regulator.

Technical Field

The invention belongs to the technical field of power quality and energy storage control, and particularly relates to an energy storage railway power regulator and a control method thereof.

Background

A Railway Power Conditioner (RPC) is a comprehensive compensation device applied to Railway electric energy quality management occasions, and can balance load active Power, compensate reactive Power and balance Power grid current. The railway power regulator based on Modular Multilevel Converter (MMC) is called MRPC, and MRPC has the advantages of high topological modularization degree, high AC output quality and small filter device, is very suitable for high-voltage and large-capacity compensation occasions, can save a step-down transformer when being connected with a traction network, and is widely used when the railway electric energy quality is controlled. If an energy storage system is added on the direct current side of the MRPC submodule, the problem of three-phase imbalance in a railway traction system can be solved, the quality of electric energy is improved, the energy of train braking can be fully utilized by the aid of the energy storage system, the efficiency of the system is improved, and the performance stability of a locomotive system is guaranteed.

Currently, in the research of the energy storage MRPC, a direct current/direct current converter (DC/DC converter) may be added to a direct current side of each MRPC submodule to connect with an energy storage device, so that the MRPC has energy storage capability. However, the number of the MRPC sub-modules is large, the energy storage cost is high by adopting the method, the running state of the MRPC is not considered when part of the energy storage systems of the sub-modules fail in the existing control method, the reliability is poor, and the control is not flexible. In addition, a Quasi-full Bridge with Integrated Battery (QFBIB) sub-module hybrid MMC topology for a wind power generation system is proposed in the literature, and an energy storage system is provided for part of sub-modules of the MMC. However, the energy storage sub-module topology is not suitable for MRPC application, and in order to reduce switching devices and enable a system to have a dc fault ride-through capability, a switching device of a sub-module energy storage device side converter is coupled with a switching state of a sub-module MMC side switching device, so that independent control of a MMC side Half-Bridge (Half Bridge, HB) converter and an energy storage side Half-Bridge converter cannot be realized, and control is complex.

Disclosure of Invention

In view of this, the embodiment of the invention provides an energy storage railway power regulator and a control method thereof, and aims to solve the problems that the energy storage railway power regulator in the prior art is high in energy storage cost, poor in reliability, complex in control and incapable of realizing independent control.

To achieve the above object, a first aspect of an embodiment of the present invention provides an energy storage railway power conditioner, including: the bridge arm comprises a first bridge arm module, a second bridge arm module and a third bridge arm module which are connected in parallel;

the first end of the first bridge arm module, the first end of the second bridge arm module and the first end of the third bridge arm module are respectively used for connecting a traction power supply network;

each bridge arm module comprises an alternating current filter inductor, an upper bridge arm submodule and a lower bridge arm submodule which have the same connecting structure and are connected in series, one end of the alternating current filter inductor is connected between the upper bridge arm submodule and the lower bridge arm submodule, and the other end of the alternating current filter inductor is used as the first end of the corresponding bridge arm module; each bridge arm sub-module comprises at least two converter units which are connected in series and have the same number, at least two converter units of at least one bridge arm sub-module in each bridge arm sub-module comprise a half-bridge converter unit and an energy storage half-bridge converter unit, and the energy storage half-bridge converter unit is formed by connecting an energy storage unit, a half-bridge converter and a direct current voltage stabilizing capacitor in parallel.

A second aspect of the embodiments of the present invention provides a control method, which is applied to the energy storage railway power regulator of the first aspect, wherein all energy storage units in the energy storage railway power regulator constitute an energy storage system, and the control method includes:

acquiring the operating parameters of the energy storage railway power regulator; the operation parameters comprise each phase load current of the electric locomotive load corresponding to the energy storage railway power regulator, each phase compensation current of the energy storage railway power regulator, first capacitance voltage of each half-bridge converter unit in the energy storage railway power regulator, and second capacitance voltage, actual current of an energy storage battery and actual charge state of the energy storage battery of each energy storage half-bridge converter unit in the energy storage railway power regulator;

carrying out current compensation processing on the load current of each phase, and calculating to obtain a first modulation signal controlled by the alternating current;

performing loop current control processing based on the compensation current of each phase, the first capacitor voltage and the second capacitor voltage, and calculating to obtain a second modulation signal for loop current control;

performing unit capacitor voltage balance control based on the first capacitor voltage, the second capacitor voltage and the actual current of the energy storage battery, performing direct current control based on the actual current of the energy storage battery and the actual charge state of the energy storage battery, and calculating to obtain a third modulation signal of unit control;

and generating a second control signal of the half-bridge converter unit and a first control signal of an energy storage unit in the energy storage half-bridge converter unit according to the first modulation signal, the second modulation signal and the third modulation signal.

Compared with the prior art, the embodiment of the invention has the following beneficial effects: compared with the prior art, each bridge arm sub-module of the energy storage railway power regulator comprises at least two converter units which are connected in series and have the same number, at least two converter units of at least one bridge arm sub-module in each bridge arm sub-module comprise both a half-bridge converter unit and an energy storage half-bridge converter unit, and the energy storage half-bridge converter unit is formed by connecting an energy storage unit, a half-bridge converter and a direct current voltage-stabilizing capacitor in parallel, namely, the number of the energy storage half-bridge converter units in the bridge arm sub-module can be set arbitrarily as long as the number of the converter units in each bridge arm sub-module is ensured to be the same. The switching state decoupling of the switching devices in the half-bridge converter and the energy storage unit can be realized while the energy storage cost is reduced, the independent control of the half-bridge converter and the energy storage unit is realized, and the independent control of the output power of the energy storage unit in the energy storage half-bridge converter unit is further realized. And the flexibility of the topological structure and the control method of the energy storage railway power regulator is further improved, the control method of the energy storage railway power regulator with simple design and control and strong universality is facilitated, and the reliability of the energy storage railway power regulator is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

FIG. 1 is a structural topology diagram of an energy storage railway power conditioner provided by an embodiment of the invention;

fig. 2 is a schematic structural diagram of an energy storage half-bridge converter unit according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a half-bridge converter unit according to an embodiment of the present invention;

FIG. 4 is a schematic flow chart of an implementation of a control method of an energy storage railway power conditioner provided by an embodiment of the invention;

FIG. 5 is an overall control block diagram of an energy storage railway power conditioner provided by an embodiment of the invention;

FIG. 6 is an AC current control block diagram provided by an embodiment of the present invention;

FIG. 7 is a block diagram illustrating the generation of a compensated current reference command according to an embodiment of the present invention;

FIG. 8 is a flowchart illustrating the calculation of the first equivalent current and the second equivalent current according to an embodiment of the present invention;

FIG. 9 is a block diagram of circulation control provided by an embodiment of the present invention;

fig. 10 is a block diagram of generation of a phase equalization control signal and a bridge arm equalization control signal according to an embodiment of the present invention;

FIG. 11 is a control block diagram of cell capacitor voltage equalization control and direct current control provided by an embodiment of the present invention;

FIG. 12 is a block diagram of the generation of a first control signal and a second control signal provided by an embodiment of the present invention;

fig. 13 is a waveform diagram of a secondary side current of a traction transformer corresponding to a simulation condition 1 according to an embodiment of the present invention;

fig. 14 is a waveform diagram of a secondary side current of the traction transformer corresponding to the simulation condition 2 provided in the embodiment of the present invention;

fig. 15 is a waveform diagram of a secondary side current of the traction transformer corresponding to the simulation condition 3 provided in the embodiment of the present invention;

fig. 16 is a waveform diagram of the secondary side current of the traction transformer corresponding to the simulated condition 4 according to the embodiment of the present invention;

fig. 17 is a waveform diagram of a secondary side current of the traction transformer corresponding to the simulated condition 5 provided in the embodiment of the present invention;

FIG. 18 is a graph of capacitor voltage simulation without feedforward control according to an embodiment of the present invention;

FIG. 19 is a graph of capacitor voltage simulation with feed forward control provided by an embodiment of the present invention;

fig. 20 is a waveform diagram of an actual current of an energy storage battery provided by an embodiment of the invention;

fig. 21 shows each HBIB converter unit SOC of the b-phase upper arm sub-module according to the embodiment of the present invention_bpzA waveform diagram of (a);

fig. 22 is a waveform diagram of actual currents of energy storage cells of each HBIB converter unit of a b-phase upper bridge arm submodule according to an embodiment of the present invention;

FIG. 23 shows HBIB converter units SOC of a phase-b upper bridge arm sub-module according to another embodiment of the invention_bpzA waveform diagram of (a);

FIG. 24 is a schematic diagram of a control device applied to an energy storage railway power conditioner according to an embodiment of the present invention;

fig. 25 is a schematic diagram of a terminal device according to an embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

The electrified railway has the advantages of large passenger capacity, strong transportation capacity, safety, reliability, high punctuation rate and the like. However, the power supply mode and load characteristics of the traction power supply system bring a series of power quality problems to the railway power supply system, affect the safe and reliable operation of the load locomotive, reduce the power supply quality of the power grid, and even threaten the stable operation of the adjacent power supply/utilization systems (such as wind power plants/photovoltaic power stations).

The unbalanced current of the power grid is a main power quality problem of rail transit at present. The traction power supply network is a symmetrical three-phase power network, but the railway load is a single-phase load, so that the problem of unbalanced three-phase current is caused, and negative-sequence current is formed on the side of the power network, so that electric equipment and loads are adversely affected. The RPC can balance active current, compensate reactive current and harmonic current, and solve the problem of negative sequence current.

The traditional RPC adopts a two-level converter as a converter structure, a traction feeder needs to be connected to the converter through a step-down transformer and is limited by a switching device, and the system voltage is low and the capacity is limited. In large-capacity application occasions, a plurality of RPCs are often required to be operated in parallel, so the system cost is high and the control is complex. Based on this problem, MRPC has been proposed. Compared with the traditional RPC, the MRPC has the characteristics of high voltage level, large compensation capacity, small alternating current filter device, low device switching frequency and the like, and also has the advantages of high modularization degree, good expansibility and redundancy, no need of a step-down transformer and the like. Among the two-leg MRPC, the three-leg MRPC, and the four-leg MRPC, the three-leg MRPC has advantages of low dc bus voltage, few switching devices, simple control, low loss, and no need for an isolation transformer.

In addition, the electric locomotive generates a large amount of energy when braking. If the braking energy is dissipated, waste is generated, and the performance (such as heat generation) of the locomotive system may be deteriorated in the braking process; if the braking energy is fed back to the power grid or stored through the energy storage device, the method has important significance.

Therefore, an energy storage system is added to the traditional RPC direct current bus, and the problems of current imbalance and braking energy recovery can be solved at the same time. If an energy storage system is added on the direct current side of the MRPC sub-module, distributed energy storage of the system can be realized, the voltage of the energy storage module can be reduced, the energy storage efficiency is improved, and meanwhile the modularization degree and redundancy of the energy storage system can be increased. However, the railway power regulator based on the MMC also needs to solve the problem of balance control between sub-module capacitance voltage and battery State of Charge (SOC). In addition, the energy storage railway power regulator in the prior art also has the problems of high energy storage cost, poor reliability, inflexible control and complex control method.

In order to explain the technical means of the present invention, the following description will be given by way of specific examples.

As shown in fig. 1, an energy storage railway power conditioner 10 according to an embodiment of the present invention may include a first bridge arm module 11, a second bridge arm module 12, and a third bridge arm module 13 connected in parallel.

The first end of the first bridge arm module 11, the first end of the second bridge arm module 12 and the first end of the third bridge arm module 13 are respectively used for connecting a traction power supply network.

Each bridge arm module comprises an alternating current filter inductor L_sThe upper bridge arm submodule and the lower bridge arm submodule which have the same connecting structure and are connected in series with each other, and the alternating current filter inductor L_sOne end of the bridge arm module is connected between the upper bridge arm sub-module and the lower bridge arm sub-module, and the other end of the bridge arm module is used as the first end of the corresponding bridge arm module; each bridge arm sub-module comprises at least two converter units which are connected in series and have the same number, and at least two converter units of at least one bridge arm sub-module in each bridge arm sub-module comprise a half-bridge converter unit HB_MjkAnd an energy storage Half Bridge (HBIB) converter unit_NjkEnergy-storing half-bridge converter unit HBIB_NjkThe energy storage unit, the half-bridge converter and the direct current voltage-stabilizing capacitor are connected in parallel to form the energy storage device.

Optionally, each bridge arm submodule may further include a bridge arm filter inductor L_armBridge arm filter inductor L_armEach bridge arm submodule comprises at least two converter cells connected in series.

Since at least two converter cells of at least one of the bridge arm sub-modules of the energy storage Railway Power regulator of the present embodiment include both the half-bridge converter cells and the energy storage half-bridge converter cells, the energy storage Railway Power regulator can be referred to as a Hybrid modular multilevel converter (Hybrid MMC rail Power Conditioner, HMRPC). As shown in FIG. 1, in the figure, u_A、u_B、u_CThe three-phase power grid supplies power to the loads of the alpha-phase electric locomotive and the beta-phase electric locomotive through the V/V traction transformer, and the current of the alpha-phase load and the current of the beta-phase load are i respectively_αL、i_βL. The first end of the first bridge arm module 11, the first end of the second bridge arm module 12 and the first end of the third bridge arm module 13, i.e. the ac filter inductance L in each bridge arm module_sThe other end of the three-phase transformer is respectively used for connecting three ports of a secondary coil of the V/V traction transformer. The load is a single-phase load, so the primary side current i of the V/V traction transformer_A、i_B、i_CUnbalance, requiring compensation of the current i by each phase of HMRPC_acomp、i_bcompAnd i_ccompThe purposes of active power balance, negative sequence compensation and three-phase current balance on the power grid side are achieved.

The HMRPC provided by the embodiment of the invention has the advantages of high MRPC modularization degree, high output quality, large system capacity, low device switching frequency and capability of omitting an isolation transformer and a step-down transformer. And because the number of the converter units in each bridge arm sub-module of the energy storage railway power regulator is the same, as long as at least two converter units of at least one bridge arm sub-module contain both a half-bridge converter unit and an energy storage half-bridge converter unit, when a plurality of bridge arm sub-modules containing both a half-bridge converter unit and an energy storage half-bridge converter unit exist, the number of the HBIB converter units in each bridge arm sub-module can be configured differently, so that the energy storage cost can be reduced, and the flexibility of the topological structure of the energy storage railway power regulator can be improved. And because the energy storage half-bridge converter unit is formed by connecting the energy storage unit, the half-bridge converter and the direct-current voltage-stabilizing capacitor in parallel, the switching states of the switching devices in the half-bridge converter and the energy storage unit can be decoupled, the independent control of the half-bridge converter and the energy storage unit is realized, and the independent control of the output power of the energy storage unit in the energy storage half-bridge converter unit is further realized.

Alternatively, as shown in fig. 2, each energy storing half-bridge converter cell HBIB_NjkThe method can comprise the following steps: energy storage battery Bat and energy storage battery filter inductor L_bSwitch tube S₅Switch tube S₆Diode D₅Diode D₆Formed energy storage unit, half-bridge converter HB and DC voltage-stabilizing capacitor C₂。

Wherein, the positive pole of the energy storage battery Bat and the filter inductance L of the energy storage battery_bIs connected with the negative pole of the energy storage battery Bat respectivelyAnd a switching tube S₆Source electrode of (2), diode D₆Positive electrode, DC voltage-stabilizing capacitor C₂Is connected to the first end of the half-bridge converter HB; first end of half-bridge converter HB as energy-storage half-bridge converter unit HBIB_NjkAn input or output of; energy storage battery filter inductance L_bIs connected with the other end of the switch tube S₅Source electrode of (1) and switching tube S₆Between the drain electrodes of (1); switch tube S₅And a diode D₅Is connected with the positive pole of the switching tube S₅Respectively with a diode D₅Negative electrode of (1), DC voltage-stabilizing capacitor C₂The other end of the half-bridge converter HB is connected with the third end of the half-bridge converter HB; switch tube S₆And a diode D₆The negative electrode of (1) is connected; switch tube S₅Grid and switching tube S₆The grid of the grid is used for inputting a first control signal; second end of half-bridge converter HB as energy-storage half-bridge converter unit HBIB_NjkAn output or an input.

Alternatively, as shown in fig. 3, each half-bridge converter cell HB_MjkThe method can comprise the following steps: switch tube S₁Switch tube S₂Diode D₁And a diode D₂Formed half-bridge converter HB and capacitor C₁。

Switch tube S₁And diode D₁Is connected as the third end of the half-bridge converter HB, and a switching tube S₂Source and diode D₂The positive electrode of the half-bridge converter HB is connected with the positive electrode of the first half-bridge converter HB; switch tube S₁Source electrode and switch tube S₂The drain of the half-bridge converter HB is connected to the first terminal of the half-bridge converter HB; switch tube S₁And a diode D₁The positive electrode of (1) is connected; switch tube S₂And a diode D₂The negative electrode of (1) is connected; capacitor C₁Is connected to the third terminal of the half-bridge converter HB, a capacitor C₁Is connected to a first end of a half-bridge converter HB; switch tube S₁Grid and switching tube S₂Is used for inputting a second control signal.

Wherein a first terminal of the half-bridge converter HB is used as a half-bridge converter unitHB_MjkAn input or output of; the second terminal of the half-bridge converter HB serves as a half-bridge converter cell HB_MjkAn output or an input.

In this embodiment, the DC side of the HB converter unit and the capacitor C₁The HBIB converter unit is additionally provided with a battery energy storage structure on the basis of the HB converter unit and is connected with a direct current capacitor C through a half-bridge converter₂Connection, L_bThe filter inductor is an energy storage battery filter inductor. By means of a second control signal, the switching tube S is changed₁～S₄The switching state of the bridge arm submodule can control the output voltage of the unit to be equal to the voltage of the capacitor or zero, and the output voltage of the bridge arm submodule is equal to the sum of the output voltages of the unit. The HBIB converter unit can change the switching tube S through the first control signal₅、S₆Thereby controlling the energy storage and release of the battery. The decoupling of the switching states of the switching devices in the half-bridge converter and the energy storage unit is realized, so that the energy storage system and the HMRPC system exchange energy, and the HMRPC system further exchanges energy with a load through an alternating current end.

The HMRPC is essentially a three-phase multi-level converter, and the alternating current port voltage can be changed by controlling the bridge arm voltage, so that the alternating current is controlled, and the compensation function is realized. The stable operation of the system needs to ensure the stable output voltage of the unit and inhibit the alternating current circulation. The stable operation of the energy storage system also requires a battery current control and SOC equalization control strategy. Therefore, a control method of the energy storage railway power regulator with strong universality needs to be designed. Fig. 4 is a schematic flow chart of an implementation of a control method of an energy storage railway power regulator according to an embodiment of the present invention, where all energy storage units in the energy storage railway power regulator form an energy storage system, and the control method is described in detail as follows.

And 101, acquiring the operating parameters of the energy storage railway power regulator.

Wherein, all energy storage units in the energy storage railway power regulator form an energy storage system, and the operation parameters may include load current i of each phase of electric locomotive load corresponding to the energy storage railway power regulator_αL、i_βLCompensation current i of each phase of energy storage railway power regulator_acomp、i_bcompAnd i_ccompFirst capacitor voltage U of each half-bridge converter cell in an energy-storing railway power conditioner_{jkl_sm}And a second capacitor voltage U of each energy-storing half-bridge converter unit in the energy-storing railway power regulator_{jkz_sm}Actual current i of energy storage battery_{jkz_bat}And the actual state of charge SOC of the energy storage battery_jkz。

Wherein, the variable subscript j ═ a, b, c represents a phase, b phase or c phase in HMRPC, k ═ p, n represents upper bridge arm submodule p or lower bridge arm submodule n, l ═ 1,2, … M_jkDenotes the number of HB converter cells, M_jkThe total number of HB converter cells included in the k bridge arm sub-modules of the bridge arm module corresponding to j in HMRPC is represented, and z is 1,2, … N_jkDenotes the number of HBIB converter units, N_jkAnd the total number of HBIB converter units included in the k bridge arm sub-modules of the bridge arm module corresponding to the j in the HMRPC is shown.

In which the following variables in the energy storage railway power conditioner system are defined in connection with fig. 1 (where the voltage is referenced to feeder ground):

alpha, beta phase load voltage u_α、u_βRespectively as follows:

wherein, U_sFor the feed line voltage amplitude, ω is the grid angular frequency.

Alpha, beta phase load current i_αL、i_βLRespectively as follows:

wherein, I_α、I_βThe load current amplitude of alpha and beta phases, theta_α、θ_βIs the load power factor angle.

a. b and c phase compensating current i_acomp、i_bcompAnd i_ccompIs defined as:

wherein, I_a、I_bA, b phase compensating current amplitude, theta_a、θ_bAre respectively represented by u_α、u_βIs the compensation current phase angle of the reference phase.

Actual circulation of each phase i_jcirIs defined as:

i_jcir＝(i_jp+i_jn)/2 (4)；

wherein i_jpAnd i_jnThe bridge arm currents of the j-phase upper bridge arm submodule and the j-phase lower bridge arm submodule are respectively.

Common mode voltage u_comIs defined as:

wherein u is_a、u_bAnd u_cIs the HMRPC AC terminal voltage.

Illustratively, the overall control function of the energy storage railway power conditioner is described in conjunction with fig. 5 as follows:

the current reference instruction generation module collects alpha and beta phase load current i_αL、i_βLCalculating the compensation current reference instruction of each phase at the AC side of the HMRPCSo as to balance three-phase current on the power grid side and control the HMRPC to exchange energy with the load. Total energy per unit value of first capacitors of all converter units in HMRPCObtained and adjusted by a calculation moduleTherefore, the total capacitance energy of all converter units in the HMRPC is stabilized, and the system can operate stably.

The alternating current control module refers each phase compensation current to an instructionCompensating current i with each phase of HMRPC_jcompTo generate a first modulation signal u, to be fed to a Proportional Resonant Regulator (PR)_jcAnd controlling each phase compensation current of the HMRPC to track a given value (each phase compensation current reference instruction).

And the circulating current control module inhibits circulating current double-frequency fluctuation and balances capacitor voltage of the interphase module and capacitor voltage between the bridge arm submodules. Reference value of circulation of each phaseObtained by a calculation module and is in contact with the actual circulation current i of each phase_jcirError, interphase balance control signalBridge arm balance control signalA common input Proportional-Integral Resonant Regulator (PIR) to obtain a second modulation signal u_jccTo achieve the functions of circulation control and balance control. Changing the algorithm of the calculation module and utilizing the actual current i of the energy storage battery_{jkz_bat}The method is used for performing feedforward control on interphase balance control and bridge arm balance control as feedforward battery current, can balance the SOC of batteries between interphase and bridge arms, and can improve the equalizing effect of capacitor voltage of submodules between interphase and bridge arms.

And the unit balance control is used for balancing the capacitance voltage among all the converter units in the bridge arm submodule. Sampling a first capacitor voltage U of a half-bridge converter cell_{jkl_sm}Second capacitor voltage U of energy storage half-bridge converter unit_{jkz_sm}Calculating the average voltage of the capacitors of the bridge arm sub-modules, and adjusting the error between the average voltage of the capacitors of the bridge arm sub-modules and the first and second capacitor voltages by a Proportional-Integral (PI) Regulator to obtain a first sub-modulationSignal u_jklcAnd a second sub-modulated signal u_jkzc. First sub-modulation signal u in the final third modulation signal_jklcAnd a second sub-modulated signal u_jkzcAnd also with bridge arm current i_jkIs related to the direction of (a). The energy storage battery is controlled to work in a direct current control mode, and a first energy storage battery current reference value is given through the calculation moduleOr a second energy storage battery current reference valueAnd introducing the battery SOC balance control and the first energy storage battery current reference valueOr a second energy storage battery current reference valueAnd the actual current i of the energy storage battery_{jkz_bat}Is summed with the SOC equalization signal and a third sub-modulation signal u in the third modulation signal is generated by the PI regulator_{jkz_bat}. And adding SOC balance control into the direct current control to balance the SOC of the energy storage battery between the HBIB converter units.

Modulating the output part, the modulation signal of the half-bridge converter cell on the MMC side, i.e. the switching tube S in FIGS. 2 and 3₁～S₄Control signal of (d), from u_jc、u_jcc、u_jklcAnd u_jkzcJointly generating, under modulation, a (second control signal) switching signal S_jklAnd S_jkzRespectively controlling the switching tubes S₁、S₂And S₃、S₄。S_{jkz_bat}For the (first control signal) switching signal of the battery-side half-bridge converter unit, i.e. S₅、S₆Switching signal of (d), from u_{jkz_bat}And (4) generating.

By the control method of the energy storage railway power regulator, the purposes of balancing the current of a power grid and improving the energy utilization rate by using an energy storage system can be achieved. And in the control process, the second capacitor voltage, the actual current and the actual state of charge of the energy storage battery and the first capacitor voltage of each half-bridge converter unit are utilized, when the energy storage unit of any energy storage half-bridge converter unit fails, the corresponding energy storage unit can be directly bypassed, and therefore the reliability of the whole energy storage railway power regulator is ensured. The flexibility of the control method of the energy storage railway power regulator is improved.

The control functions of each part of the energy storage railway power regulator through the steps 102 to 105 are described as follows:

and 102, performing current compensation processing on each phase of load current, and calculating to obtain a first modulation signal for controlling the alternating current.

In this embodiment, each phase of load current is compensated by the energy storage system, the reactive current compensation, the active current balance and the negative sequence current compensation to obtain a compensated load current, and the compensated load current is subtracted from the actual load current to obtain a compensation current reference command. Reference command of compensating current for each phaseCompensating current i with each phase of HMRPC_jcompIs adjusted by the PR to form a first modulation signal u_jcAnd controlling each phase compensation current of the HMRPC to track a given value (each phase compensation current reference instruction).

Optionally, with reference to fig. 6 and 7, performing current compensation processing on the load current of each phase, and calculating to obtain a first modulation signal for controlling the ac current, may include: acquiring a first equivalent current, a second equivalent current and a capacitance reference voltage in an energy storage railway power regulator; carrying out current compensation processing according to the load current of each phase, the first equivalent current and the second equivalent current, and calculating to obtain an initial compensation current d-axis component; calculating to obtain per unit values of first capacitance total energy reference values of all converter units in the energy storage railway power regulator according to the capacitance reference voltage; calculating to obtain a per unit value of the total energy of the first capacitors of all converter units in the energy storage railway power regulator according to the first capacitor voltage and the second capacitor voltage; adjusting the d-axis component of the initial compensation current according to the per-unit value of the first capacitor total energy reference value and the per-unit value of the first capacitor total energy, and calculating to obtain the d-axis component of the compensation current; carrying out dq conversion on each phase of load current, and calculating to obtain a q-axis component of the load current; multiplying the q-axis component of the load current by-1 to obtain a q-axis component of the compensation current; carrying out dq inverse transformation according to the d-axis component and the q-axis component of the compensation current, and calculating to obtain a compensation current reference instruction of each phase; and calculating to obtain a first modulation signal controlled by the alternating current according to the compensation current of each phase and the compensation current reference instruction of each phase.

Wherein the first equivalent current i_αbOutputting equivalent current of active power on the alternating current side of the energy storage railway power regulator to the alpha phase through the energy storage railway power regulator for the energy storage system, and outputting a second equivalent current i_βbAnd outputting equivalent current of active power on the alternating current side of the energy storage railway power regulator to the beta phase through the energy storage railway power regulator for the energy storage system.

Optionally, obtaining the first equivalent current and the second equivalent current may include:

the method comprises the steps of obtaining alpha-phase load active power and beta-phase load active power of an electric locomotive load corresponding to an energy storage railway power regulator, the maximum output power of an energy storage system of the energy storage railway power regulator, the allowed maximum charge state of an energy storage battery of each energy storage half-bridge converter unit in the energy storage railway power regulator and the allowed minimum charge state of the energy storage battery.

And judging whether the active power of the alpha-phase load, the active power of the beta-phase load and the actual state of charge of the energy storage battery meet preset conditions, wherein the preset conditions are that the sum of the active power of the alpha-phase load and the active power of the beta-phase load is larger than zero and the actual state of charge of each energy storage battery is larger than the corresponding allowable minimum state of charge of the energy storage battery, or the sum of the active power of the alpha-phase load and the active power of the beta-phase load is smaller than zero and the actual state of charge of each energy storage battery is smaller than the corresponding allowable maximum state of charge of the energy storage battery.

If the active power of the alpha-phase load, the active power of the beta-phase load and the actual state of charge of the energy storage battery meet preset conditions, calculating to obtain an absolute value of the difference between the active power of the alpha-phase load and the active power of the beta-phase load, and judging whether the absolute value is less than or equal to the maximum output power of the energy storage system.

If the absolute value is less than or equal to the maximum output power of the energy storage system, the method is based onAnd acquiring a first equivalent current and a second equivalent current.

If the absolute value is greater than the maximum output power of the energy storage system, the method is based onAnd acquiring a first equivalent current and a second equivalent current.

And if the alpha-phase load active power, the beta-phase load active power and the actual charge state of the energy storage battery do not meet the preset conditions, determining that the first equivalent current and the second equivalent current are both zero.

Wherein i_αbIs a first equivalent current, i_βbIs the second equivalent current, P_bmFor maximum output power of the energy storage system, U_sFor the amplitude of the feed line voltage, P_αLFor alpha-phase load active power, P_βLFor beta-phase loaded active power, F₁＝sin(ωt-π/6)，F₂Sin (ω t-pi/2), ω is the grid angular frequency, f₁、f₂、f₃Are coefficients.

In conjunction with FIG. 8, in this figure "&&"represents a logical AND", "|" represents a logical OR ", P_bmFor the maximum output power of the energy storage system, which can be obtained directly, P_αLAnd P_βLFor the alpha and beta phase load active power, it can be calculated by equation (6), i_αLdAnd i_βLdIs alpha and beta phase load active current and is obtained by current active separation, SOC_jkz、SOC_maxAnd SOC_minThe actual SOC of the energy storage battery, the allowed maximum SOC of the energy storage battery and the allowed minimum SOC of the energy storage battery of the HBIB converter unit are respectively.

Wherein, I_αLd、I_βLdThe active current amplitude of the alpha and beta phase load is obtained.

Firstly, judging whether the SOC of the energy storage system meets the energy storage or release condition. If P_αL+P_βL>0, namely the total alpha and beta phase load consumes active power, and at the moment, if the actual SOC of each energy storage battery meets the SOC_jkz>SOC_minThe energy storage device allows for energy release; if P_αL+P_βL<0, indicating that the alpha and beta phase total load feeds back active power to the power grid, and if the SOC is in the moment_jkz<SOC_maxThe energy storage device allows energy storage; otherwise let i_αb＝i_βbAnd 0, namely the energy storage system does not work.

And further judging whether the energy storage system can balance the active power of the alpha phase and the beta phase. If P_αL-P_βL|≤P_bmThe active power of the alpha phase and the active power of the beta phase are equal after the energy storage system is compensated; if P_αL-P_βL|>P_bmAnd the absolute value of the active power of the compensation load of the energy storage system is larger. Thus, i can be calculated from FIG. 8_αbAnd i_βbIn the figure, F₁＝sin(ωt-π/6)，F₂＝sin(ωt-π/2)，f₁、f₂And f₃Is a coefficient, the calculation formula is:

before and after the energy storage system works, active power output by HMRPC to alpha and beta phases is changed, and negative sequence compensation is performedThe force will also change. The present embodiment therefore prioritizes the compensation effect of the energy storage system when calculating the compensation current. In FIG. 7, the α, β phase load current i_αLAnd i_βLRespectively with the first equivalent current i_αbAnd a second equivalent current i_βbAdding the energy storage system and giving priority to the compensation of the energy storage system to obtain the current after the compensation of the energy storage system, and recording the current as i_αlAnd i_βlAnd then calculating the compensation reactive current, the negative sequence current and the balance active current of the HMRPC. Specifically, for i_αlAnd i_βlPerforming active power separation according to the instantaneous reactive power theory to obtain a current i after reactive power compensation_αlpAnd i_βlp. Therefore, the grid current is calculated by the formula (8) according to the alpha and beta load currents, then the grid current is converted to a dq coordinate system by the formula (9), and a direct-current component of the d-axis current is extracted by a Second-Order generalized Integrator (SOGI) and multiplied by a proportionality coefficient G to obtain I_d。I_dI is the compensated three-phase power grid is balanced i_αlAnd i_βlAnd d-axis component in dq coordinate system, and q-axis component after compensation is zero. And finally, respectively subtracting the compensated load current from the load current of each phase under the dq coordinate system to obtain the initial compensation current. Specifically, i is_αLAnd i_βLTransformation into dq coordinate system, I_dWith the d-axis component i of the load current_dSubtracting to obtain an initial compensation current d-axis component, adjusting the initial compensation current d-axis component according to the per-unit value of the first capacitance total energy reference value and the per-unit value of the first capacitance total energy, and calculating to obtain a compensation current d-axis component; load current q-axis component i_qMultiplying-1 to obtain a q-axis component of the compensation current, and performing inverse transformation on the obtained d and q-axis components of the compensation current to obtain a final reference instruction of each phase of the compensation currentIn FIG. 7, the scale factorTheta is phase-locked u_APhase, i_ddFor the current after the compensation and reactive compensation of the energy storage systemThe d-axis component.

Wherein k is_tIs the transformation ratio of the traction transformer.

Wherein i_dAnd i_qRespectively, a d-axis component and a q-axis component of the load current in a dq coordinate system.

On the basis, a capacitance total energy control loop can be introduced into the generation of each phase of compensation current reference instruction, the d-axis component of the initial compensation current is adjusted according to the per-unit value of the first capacitance total energy reference value and the per-unit value of the first capacitance total energy, and the d-axis component of the compensation current is obtained through calculation and is used for balancing the total capacitance of the system capacitor. In the context of figure 7 of the drawings,is the per unit value of the first capacitance total energy reference value of all the converter units in the energy storage railway power regulator,and summing the difference value of the per unit value of the total energy of the first capacitors of all the converter units in the energy storage railway power regulator and the initial compensation current d-axis component through a PI regulator to obtain a compensation current d-axis component so as to stabilize the total capacity of the capacitors.Andthe calculation formula of (a) is as follows:

wherein the content of the first and second substances,the reference voltage is a capacitance reference voltage in the energy storage railway power regulator.

In this embodiment, when the system is stable, the HMRPC outputs power to the load and is equal to the output power of the energy storage system, and because the battery is controlled by direct current, the output power of the energy storage system is equal to the power expected to be output by the energy storage system under the operation of the calculation module, the total energy outer ring of the capacitor does not play a role basically when being stable, and the tracking and giving of the output power of the energy storage system are not affected, so that the total energy outer ring of the capacitor can be retained in this embodiment, and the total capacity of the capacitor is stabilized.

And 103, performing circulation control processing based on the compensation current of each phase, the first capacitor voltage and the second capacitor voltage, and calculating to obtain a second modulation signal for circulation control.

Referring to fig. 9, a circulating current reference value of each phase can be calculated based on the compensation current of each phase, the first capacitor voltage and the second capacitor voltagePhase equalization control signalAnd bridge arm balance control signalReference value of circulation of each phaseWith actual circulation of each phase i_jcirThe error value of the bridge arm sub-module is equal to the phase equalization control signal formed by the interphase capacitance voltage equalization control and the bridge arm sub-module capacitance voltage equalization controlAnd bridge arm balance control signalSummed as an input to a PIR regulator to form a second modulated signal u_jccThe direct current circulation is stabilized, the secondary circulation is restrained, and the capacitor voltage between phases and between bridge arm submodules is balanced.

Optionally, with reference to fig. 9 and fig. 10, performing a loop current control process based on the compensation current of each phase, the first capacitor voltage, and the second capacitor voltage, and calculating to obtain a second modulation signal for loop current control may include: decomposing the compensation current of each phase, and calculating to obtain a circulation reference value of each phase according to a decomposition result; calculating to obtain a per unit value of the total second capacitance energy of all the converter units in each upper bridge arm sub-module and a per unit value of the total third capacitance energy of all the converter units in each lower bridge arm sub-module according to the first capacitance voltage and the second capacitance voltage; calculating a per unit value of a total energy reference value of the second capacitor of each bridge arm module according to the obtained capacitor reference voltage; performing proportional integral adjustment according to the difference between the sum of the per-unit value of the total energy of the second capacitor and the per-unit value of the total energy of the third capacitor and the per-unit value of the total energy reference value of the second capacitor, and calculating to obtain a phase equilibrium control power reference value of each phase; calculating to obtain a phase equalization control signal of each phase according to the phase equalization control power reference value; performing proportional integral adjustment according to the difference between the per-unit value of the total energy of the second capacitor and the per-unit value of the total energy of the third capacitor, and calculating to obtain a bridge arm balance control power reference value of each phase; calculating to obtain bridge arm balance control signals of each phase according to the bridge arm balance control power reference value; and regulating the acquired actual circulation of each phase, the circulation reference value of each phase, the phase balance control signal of each phase and the bridge arm balance control signal of each phase of the energy storage railway power regulator through the proportional-integral resonance regulator, and calculating to obtain a second modulation signal for circulation control.

Wherein each phase of the energy storage railway power regulator is actually circulated i_jcirThe actual circulation current i of each phase can be calculated according to the formula (4) or directly obtained by measurement_jcir。

The process of decomposing the compensation current of each phase and calculating the circulating current reference value of each phase according to the decomposition result may be as follows:

the active current and the reactive current of the a and b phase compensation currents in the formula (3) are decomposed to obtain:

wherein, I_P1For the amplitude of the same phase component of the a-phase compensation current and the alpha-phase load voltage, I_Q1Compensating the current lag alpha phase load voltage phase for the a phase by 90 DEG current component amplitude; i is_P2For the b-phase compensation current and the beta-phase load voltage with the same phase component amplitude, I_Q2The phase of the beta-phase load voltage is 90 DEG in current component amplitude for the phase b compensation current lag.

Calculating j-phase instantaneous power P_jComprises the following steps:

P_j＝U_dci_jcir+(u_j+u_com)i_jcomp (13)；

wherein, U_dcIs the dc bus voltage.

Synthesizing formulas (1), (5), (12) and (13), and solving to obtain a three-phase circulation reference value according to that when the HMRPC system works stably, j-phase instantaneous power has no direct current component, namely the direct current component in the formula is 0

With reference to fig. 10, the interphase balance control and the bridge arm balance control can ensure stable capacitance and voltage between interphase and bridge arm submodules, and can be realized by controlling direct current circulating current and fundamental wave alternating current circulating current respectively. In the following analysis, the capacitance per unit energy values of the HB and HBIB converter cells are defined asAndper unit value is used as superscript^#And (4) showing.

Wherein, each corresponding upper bridge arm submodule of the MMC has a per unit value of the total energy of the second capacitors of all the converter unitsAnd the per unit value of the total energy of the third capacitors of all the converter units in the lower bridge arm sub-moduleCan be calculated as:

phase equalization of phases controls phase power reference values for phase sub-module capacitive energy balancingThe following can be calculated by the PI regulator:

wherein the content of the first and second substances,is the per unit value of the total energy reference value of the second capacitor of each corresponding bridge arm module,is the per unit value of the total energy of the second capacitorAnd per unit value of total energy of third capacitorSum, k_p1、k_i1Respectively are a proportional coefficient and an integral coefficient of interphase balance control.

Then the control signals are equalized between phasesComprises the following steps:

per unit value of total energy of second capacitorAnd per unit value of total energy of third capacitorThe difference value of the bridge arm balance control power reference value can be calculated through a PI regulatorComprises the following steps:

wherein k is_p2、k_i2Respectively are a proportional coefficient and an integral coefficient of bridge arm balance control.

The degree of freedom of the alternating current circulation is 3, wherein the fundamental wave positive sequence circulation and the fundamental wave negative sequence circulation can be used for bridge arm balance control, and bridge arm balance control signals are setThe expression is as follows:

wherein, I_z+、I_z-Positive and negative sequence circulating current amplitudes, theta, respectively₊、θ_-Positive sequence circulating phase angle and negative sequence circulating phase angle.

Let theta₊When 0, we get:

wherein the content of the first and second substances,

optionally, with reference to fig. 10, before the calculating the phase equalization control signal of each phase according to the phase equalization control power reference value, the method may further include:

and calculating to obtain the total current of the first energy storage battery of each upper bridge arm submodule, the total current of the second energy storage battery of each lower bridge arm submodule, the total current of the third energy storage battery of each bridge arm module and the average current of the energy storage batteries of each bridge arm module in the energy storage railway power regulator according to the actual current of the energy storage batteries.

The calculating the phase equalization control signal of each phase according to the phase equalization control power reference value may include: performing proportional feedforward adjustment according to the difference between the total current of the third energy storage battery and the average current of the energy storage battery, and calculating to obtain a first adjustment result; and correcting the phase balance control power reference value according to the first adjustment result, and calculating to obtain the phase balance control signal of each phase according to the corrected phase balance control power reference value.

The calculating to obtain the bridge arm balance control signal of each phase according to the reference value of the bridge arm balance control power may include: performing proportional feedforward adjustment according to the difference between the total current of the first energy storage battery and the total current of the second energy storage battery, and calculating to obtain a second adjustment result; and correcting the bridge arm balance control power reference value according to the second regulation result, and calculating to obtain bridge arm balance control signals of each phase according to the corrected bridge arm balance control power reference value.

When the number of the HBIB converter units included in different corresponding bridge arm modules or different bridge arm sub-modules is different, or the power of the energy storage batteries of different HBIB converter units is different, the energy stored or released by the energy storage system is transferred between the HB and HBIB converter units, and also transferred between phases and among the bridge arm sub-modules.

Wherein i_{jkz_bat}When the actual current of the energy storage battery is positive, the capacitor corresponding to the energy storage half-bridge converter unit releases energy, the voltage of the capacitor drops, and the voltage of the capacitor corresponding to the energy storage half-bridge converter unit needs to be increased; when the actual current of the energy storage battery is negative, the capacitor voltage of the corresponding energy storage half-bridge converter unit rises, and the capacitor voltage of the corresponding energy storage half-bridge converter unit needs to be reduced. Taking all energy storage half-bridge converter units of all corresponding bridge arm modules or bridge arm sub-modules into consideration as a whole, and calculating the total current i of the first energy storage battery of each upper bridge arm sub-module in the energy storage railway power regulator_{jp_bat}And the total current i of the second energy storage battery of each lower bridge arm submodule_{jn_bat}And the total current i of the third energy storage battery of each bridge arm module_{j_bat}And average current i of energy storage batteries of each bridge arm module_{phav_bat}Respectively as follows:

if the total current i of the third energy storage battery_{j_bat}Is larger than the average current i of the energy storage battery_{phav_bat}If the energy storage power of the phase energy storage system is larger than the three-phase average value or the energy release power of the phase energy storage system is smaller than the three-phase average value, the average value of the capacitor voltage of the phase module is reduced compared with the average value of the capacitor voltage of all modules of the system, and the average voltage of the capacitor of the phase module needs to be increased; if the total current i of the third energy storage battery_{j_bat}Less than the average current i of the energy storage battery_{phav_bat}The phase module average voltage needs to be reduced.

When the total current i of the first energy storage battery_{jp_bat}Is larger than the total current i of the second energy storage battery_{jn_bat}When necessary, an upper bridge needs to be addedThe average voltage of the arm sub-modules is reduced, and the average voltage of the lower bridge arm sub-modules is reduced; when the total current i of the first energy storage battery_{jp_bat}Is less than the total current i of the second energy storage battery_{jn_bat}And when the voltage of the upper bridge arm submodule is required to be reduced, the average voltage of the lower bridge arm submodule is required to be increased.

Thus, equations (16) and (18) are rewritten, and battery current proportional feedforward control is introduced to obtain a modified phase balance control power reference value and a modified bridge arm balance control power reference value as follows:

wherein k is_p3The proportionality coefficient is feedforward controlled for the phase battery current.

Wherein k is_p4And the proportional coefficient is feedforward controlled for the current of the bridge arm battery.

Substituting the formula (22) and the formula (23) into the formulas (17), (19) and (20), respectively, to obtain the phase equalization control signalAnd bridge arm balance control signalThe obtained phase equalization control signalAnd bridge arm balance control signalThe method has the battery current feedforward control effect, can accelerate the energy balance of the energy storage system between the interphase bridge arm module and the bridge arm sub-module, improves the exchange speed of the energy storage system between the HMRPC interphase and the bridge arm, and is beneficial to stabilizing the capacitance voltage of the sub-module.

And 104, performing unit capacitor voltage balance control based on the first capacitor voltage, the second capacitor voltage and the actual current of the energy storage battery, performing direct current control based on the actual current of the energy storage battery and the actual charge state of the energy storage battery, and calculating to obtain a third modulation signal for unit control.

In this embodiment, as shown in fig. 11, the HB converter unit capacitance voltage equalization is implemented by changing the unit modulation wave, and similarly, the HBIB converter unit may also change the unit modulation wave to implement the capacitance voltage equalization. In order to further accelerate the unit capacitor voltage balancing speed, battery current feedforward control is introduced, the influence of an energy storage battery in an HBIB converter unit on the unit capacitor voltage when the energy storage battery works is added into a balancing control strategy in a battery current feedforward mode, the modulation waves of the HB converter unit and the HBIB converter unit can be quickly adjusted when the battery current changes, the unit energy transfer is accelerated, and the capacitor voltage balancing speed is improved. The energy storage battery of the HBIB converter unit adopts direct current control, and introduces battery SOC balance control.

Optionally, the cell capacitor voltage equalization control is performed based on the first capacitor voltage, the second capacitor voltage and the actual current of the energy storage battery, the direct current control is performed based on the actual current of the energy storage battery and the actual state of charge of the energy storage battery, and a third modulation signal for cell control is obtained through calculation, which may include: obtaining bridge arm current of each bridge arm submodule in the energy storage railway power regulator; calculating to obtain the average energy storage battery current of the bridge arm of each bridge arm submodule in the energy storage railway power regulator according to the actual current of the energy storage battery; calculating to obtain the average voltage of the capacitor of each bridge arm submodule in the energy storage railway power regulator according to the first capacitor voltage and the second capacitor voltage; adjusting according to the first capacitor voltage, the capacitor average voltage, the bridge arm average energy storage battery current and the bridge arm current, and calculating to obtain a first sub-modulation signal of each half-bridge converter unit in the energy storage railway power regulator; adjusting according to the second capacitor voltage, the actual current of the energy storage battery, the average voltage of the capacitor, the average current of the bridge arm energy storage battery and the bridge arm current, and calculating to obtain a second sub-modulation of each energy storage half-bridge converter unit in the energy storage railway power regulatorSignal preparation; calculating to obtain the average charge state of the energy storage batteries of all energy storage half-bridge converter units in the energy storage railway power regulator according to the actual charge state of the energy storage batteries; according toCalculating to obtain a first energy storage battery current reference value; adjusting according to the first energy storage battery current reference value, the energy storage battery actual current, the energy storage battery actual state of charge and the energy storage battery average state of charge, and calculating to obtain a third sub-modulation signal of each energy storage half-bridge converter unit in the energy storage railway power regulator; and taking the first sub-modulation signal, the second sub-modulation signal and the third sub-modulation signal as a third modulation signal for unit control.

Wherein, I_αbIs the first equivalent current amplitude, I_βbFor the second equivalent current amplitude, U_batIs the energy storage battery voltage.

In this embodiment, the average current i of the energy storage battery of the bridge arm of each bridge arm submodule in the energy storage railway power regulator is defined_{jk_batav}：

Actual current i of energy storage battery_{jkz_bat}When the voltage of the unit capacitor is positive, the voltage of the unit capacitor is in a descending trend, and the voltage of the unit capacitor needs to be increased; actual current i of energy storage battery_{jkz_bat}When the voltage is negative, namely the energy storage battery discharges, the voltage of the unit capacitor needs to be reduced. When the actual current of the energy storage battery (the actual current of the energy storage battery of the HB converter unit is recorded as 0) is larger than the average current i of the energy storage battery of the bridge arm_{jk_batav}When the voltage of the unit capacitor needs to be increased, the voltage is less than the average energy storage battery current i of the bridge arm_{jk_batav}The cell capacitor voltage is reduced, thereby obtaining a battery current feed-forward control method. The actual current i of the energy storage battery_{jkz_bat}(HB converter unit is 0) and bridge arm average energy storage battery current i_{jk_batav}The difference value of the voltage difference is used as a battery feedforward control signal through a proportional regulator, and a regulating unit modulates the signal to achieve feedforward controlThe purpose of the preparation is.

Capacitor average voltage U of bridge arm submodule in energy storage railway power regulator_{jk_armav}Comprises the following steps:

average voltage U of capacitor_{jk_armav}And a first capacitor voltage U_{jkl_sm}Is summed with the battery feed-forward control signal through the PI regulator as a first initial sub-modulation signal for each HB converter unit in the energy storage railway power regulator. Bridge arm current i_jkInfluence the final first sub-modulated signal u_jklcPositive and negative of (1)_jkIf the voltage is positive, multiplying the first initial sub-modulation signal by 1, and increasing the duty ratio of the converter unit with lower unit capacitor voltage to increase the charging time; i.e. i_jkWhen negative, the first initial sub-modulation signal is multiplied by-1, reducing its discharge time. The HBIB converter unit is similar to the HB converter unit in capacitor voltage balance control and outputs a second sub-modulation signal u_jkzc。

Average state of charge (SOC) of energy storage batteries of all energy storage half-bridge converter units in energy storage railway power regulator_avComprises the following steps:

in the embodiment, direct current control is adopted to add SOC balance control so as to balance the SOC of the energy storage battery between the HBIB converter units. Controlling the actual current of the energy storage batteries of all the HBIB converter units to be the same according toCalculating to obtain a first energy storage battery current reference valueFirst energy storage battery current reference valueAnd the actual current i of the energy storage battery_{jkz_bat}Is summed with the SOC equalization signal and a third sub-modulation signal u is generated by a PI regulator_{jkz_bat}. And adding SOC balance control into the direct current control to balance the SOC of the energy storage battery between the HBIB converter units. Specifically, SOC_avAnd SOC_jkzAnd (4) performing difference making, using the difference as an SOC balance signal through a PI regulator, and controlling the charging and discharging current of the energy storage battery to realize SOC balance.

Optionally, after the first energy storage battery current reference value is obtained through calculation, the method may further include:

according toAnd calculating to obtain a second energy storage battery current reference value.

Wherein the content of the first and second substances,for controlling the current reference value, SOC (state of charge) of a second energy storage battery with different energy storage battery currents of a z-th energy storage half-bridge converter unit in a k-bridge arm submodule of a j corresponding bridge arm module in the energy storage railway power regulator_jkzThe actual state of charge, SOC, of the energy storage battery of the z-th energy storage half-bridge converter unit in the k bridge arm submodule of the bridge arm module corresponding to j in the energy storage railway power regulator_avThe average charge state of the energy storage battery is obtained;

adjusting according to the first energy storage battery current reference value, the energy storage battery actual current, the energy storage battery actual state of charge and the energy storage battery average state of charge, and calculating to obtain a third sub-modulation signal of each energy storage half-bridge converter unit in the energy storage railway power regulator, wherein the method comprises the following steps:

and adjusting according to the current reference value of the second energy storage battery, the actual current of the energy storage battery, the actual state of charge of the energy storage battery and the average state of charge of the energy storage battery, and calculating to obtain a third sub-modulation signal of each energy storage half-bridge converter unit in the energy storage railway power regulator.

In this embodiment, when the HMRPC and the energy storage system thereof work, the HMRPC and the energy storage system thereof may also workSo as to balance the SOC of the energy storage battery by controlling the actual current of the energy storage battery of the HBIB converter unit to be different. Actual state of charge SOC of energy storage battery of HBIB converter unit_jkzLower than average state of charge SOC of energy cell_avAnd when the HBIB converter unit energy storage battery is charged, the charging current is controlled to be larger than the average charging current, and the discharging current is controlled to be smaller than the average discharging current. However, the total charging or discharging current of all HBIB converter units should remain unchanged to ensure that the total power of the energy storage system for storing or releasing energy is unchanged when the SOC is equalized.

Therefore, the reference value of the current of the second energy storage battery can be calculated according to the following formula

Using the second energy-storing battery current reference valueInstead of the first energy storage battery current reference in fig. 11The SOC of the energy storage battery can be balanced by controlling the actual current of the energy storage battery of the HBIB converter unit to be different.

And 105, generating a second control signal of the half-bridge converter unit and a first control signal of an energy storage unit in the energy storage half-bridge converter unit according to the first modulation signal, the second modulation signal and the third modulation signal.

Illustratively, as shown in FIG. 12, the first modulation signal u is generated by AC current control_jcThe modulation signals of the upper and lower bridge arm submodules are reversed and respectively connected with a second modulation signal u for circulation control_jccMaking a difference with the first sub-modulation signal u_jklcA second sub-modulation signal u_jkzcSumming, generating a half-bridge switching signal (second control signal) S on the MMC side by carrier phase shift modulation_jkl、S_jkz. Third sub-modulated signal u_{jkz_bat}Generating an energy storage battery side switching signal (first control signal) S by Pulse Width Modulation (PWM)_{jkz_bat}。

The control method of the energy storage railway power regulator is further described by the specific embodiment.

The PSCAD and MATLAB Simulink are used for simulation, the topology of a simulation circuit is shown in figure 1, the secondary side of a V/V transformer is used as a voltage source for simulation, and the voltage of a feeder line is 27.5 kV. The simulation circuit parameters are shown in table 1.

TABLE 1 three-bridge arm energy storage HMRPC simulation parameters

And designing a simulation working condition of 1-4, wherein the simulation time is 6s, the HMRPC is put into operation when 0.5s, the energy storage system is put into operation when 2s, and the simulation step length is 1 e-5. And calculating to obtain a compensation current reference instruction as a given value, wherein the compensation current reference instruction is used for verifying the feasibility and the effectiveness of the energy storage HMPRC and the control method thereof. The load power and the energy storage system power under the simulation working conditions of 1-4 are shown in table 2, and the power of each energy storage device is controlled to be the same.

The secondary side currents of the traction transformer under the four simulation working conditions are respectively shown in fig. 13-16. In each operating mode, three waveform diagrams (namely, (a1), (a2), (a3) in fig. 13, (b1), (b2) and (b3) in fig. 14, (c1), (c2) and (c3) in fig. 15 and (d1), (d2) and (d3) in fig. 16) are respectively the secondary side current waveforms of the traction transformer when the energy storage system is not operated, the HMRPC is operated and the HMRPC is operated before the HMRPC is operated. From the figure, it can be seen that: after the MRPC is put into operation, the three-phase current is balanced (the load current is completely compensated under the working condition 1). Meanwhile, after the energy storage system is put into use, the power consumed by the load is reduced (working condition 2), or the power fed back to the power grid energy by the load is reduced (working conditions 3 and 4).

TABLE 2 three-bridge arm energy storage HMRPC simulation parameters

The simulation working condition 5 simulates the working state of the HMRPC system when the power of different energy storage devices is different, the simulation time is 6s, the HMPRC is put into use when 0.5s, and the energy storage system is put into use when 2.5 s. As shown in (e1) and (e2) in fig. 17, after MRPC compensation is performed, the three-phase currents have the same amplitude and phase difference of 120 °, and after the energy storage system is operated, the compensation current reference command is changed, so that the output power of the energy storage system is 1.6MW, which is 10% of the total load. The amplitude of the three-phase current is reduced from about 478.1A to about 429.9A, which proves that the energy storage system compensation is effective and the three-phase current is still balanced.

The total compensation power of the energy storage battery is 1.6MW, and a second energy storage battery current reference value of the energy storage battery of each HBIB converter unit in the upper bridge arm submodule and the lower bridge arm submodule in the corresponding bridge arm module is givenIs 6.69A, b corresponding to the second energy storage battery current reference value of the energy storage battery of each HBIB converter unit in the upper bridge arm submodule and the lower bridge arm submodule in the bridge arm module106.69A, c corresponds to the second energy storage battery current reference value of the energy storage battery of each HBIB converter unit in the upper bridge arm sub-module in the bridge arm module92.69A, c corresponds to the second energy storage battery current reference value of the energy storage battery of each HBIB converter unit in the lower bridge arm sub-module in the bridge arm moduleIt was 20.69A. And verifying the effectiveness of the battery current feedforward control, and respectively simulating the working conditions with feedforward control and without feedforward control under the condition that the system topology and other control systems are the same.

Fig. 18 (a) and 19 (b) show capacitance voltage waveforms of a plurality of HB converter cells and HBIB converter cells in an upper arm sub-module in an arm module corresponding to b, fig. 18 (c) and 19 (d) show capacitance average voltage waveforms of upper and lower arm sub-modules in an arm module corresponding to c, and fig. 18 (e) and 19 (f) show capacitance average voltage waveforms of the respective arm modules corresponding to each other. As can be seen from fig. 18 and 19, after the feedforward control is introduced, when the energy storage system is put into operation, the speed of equalizing the capacitance and the voltage between the HBIB and the HB converter units, between the bridge arm sub-modules, and between the corresponding bridge arm modules is increased, and the effect of equalizing the capacitance and the voltage is better. Before and after the energy storage system is put into operation, capacitance and voltage between HBIB and HB converter units, between bridge arm sub-modules and between corresponding bridge arm modules can be stabilized near the reference value under the equilibrium control strategy.

Fig. 20 is a waveform diagram of an actual current of the energy storage battery, the actual current of the energy storage battery is not only related to a given value, but also affected by an SOC equalization control strategy, and the amplitude of the equalization control on the actual current of the energy storage battery is limited to ± 10A. As shown in fig. 21, the actual SOC of each HBIB converter unit energy storage battery of the b-phase upper bridge arm submodule is respectively set to 49.85%, 49.9%, 49.95%, 50%, 50.05%, 50.1%, and 50.15%, and the actual SOC of the remaining energy storage batteries is set to 50%. As can be seen from fig. 20 and 21, under the SOC equalization control strategy, the SOCs tend to be consistent, and under the condition that the actual currents of the energy storage batteries of the HBIB converter units are different, the equalization control is performed with the purpose of equalizing the SOCs of all the batteries of the HMRPC system.

And under the working condition 6, the SOC is balanced by adopting a method for controlling the battery current, the upper bridge arm submodule of the bridge arm module corresponding to the b is taken as a research object, and the energy storage battery current waveform diagram and the energy storage battery SOC waveform diagram of the upper bridge arm submodule of the bridge arm module corresponding to the b are respectively shown in fig. 22 and 23. Therefore, the SOC of the batteries is different, and the output current of the batteries is controlled to be different so as to balance the SOC of the batteries. Under the SOC balance control strategy, the working condition 6 is more rapid in battery SOC balance compared with the working condition 5.

According to the control method of the energy storage railway power regulator, the power output by the HMRPC to the load is calculated according to the load condition, the first equivalent current and the second equivalent current are calculated, the compensation effect of the energy storage system is considered preferentially according to the first equivalent current and the second equivalent current, active balance, reactive power and negative sequence compensation are carried out, and the compensation current reference instruction of each phase for alternating current control is calculated. Meanwhile, energy output by the HMRPC to the load needs to be provided by the energy storage system, the energy storage battery is controlled by direct current, the output power of the energy storage system is equal to the power output by the HMRPC to the load, and then the current reference value of the first energy storage battery or the current reference value of the second energy storage battery is obtained through calculation according to the first equivalent current and the second equivalent current. And the compensation current reference instruction of each phase and the current reference value of the first energy storage battery or the current reference value of the second energy storage battery synchronously change, so that the control method for actively compensating the energy exchanged between the HMRPC and the load by the energy storage system is obtained. The physical quantity change and energy transfer principle of the system under the control method are analyzed: when the compensation current reference instruction of each phase changes, the output power of the load to the HMRPC is positive (negative), at the moment, the capacitor voltage of the HMRPC converter unit has a rising (lowering) trend, the direct current voltage of the corresponding HBIB converter unit is lowered (raised) under the charging (discharging) action of the energy storage battery, the voltage of the converter unit of the HB converter unit is raised (lowered) due to the fact that the energy storage device is not arranged, but the voltages of the HBIB converter unit and the HB converter unit finally tend to be consistent under the balancing control action, and the energy exchange of the load and the energy storage system is achieved. According to the control method provided by the embodiment of the invention, because the compensation current reference instruction of each phase and the current reference value of the first energy storage battery or the current reference value of the second energy storage battery are synchronously changed, the output power of the energy storage system is equal to the output power of the HMRPC to the load, and the energy stability of the HMRPC system is favorably ensured. And the current stability of the energy storage battery can be ensured, the service life of the energy storage battery can be prolonged, and the SOC balance control under the direct current control is easier to realize. Meanwhile, different output powers of different HBIB converter units can be controlled by adopting direct current control, and the flexibility and the reliability of the control method of the energy storage railway power regulator are improved.

It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

The following are embodiments of the apparatus of the invention, reference being made to the corresponding method embodiments described above for details which are not described in detail therein.

Fig. 24 shows a schematic diagram of a control device applied to an energy storage railway power regulator according to an embodiment of the present invention, corresponding to the control method applied to the energy storage railway power regulator described in the above embodiment. As shown in fig. 24, the apparatus may include: an acquisition module 241, a first processing module 242, a second processing module 243, a third processing module 244, and a control signal generation module 245.

An obtaining module 241, configured to obtain an operating parameter of the energy storage railway power regulator; the operation parameters comprise each phase load current of the electric locomotive load corresponding to the energy storage railway power regulator, each phase compensation current of the energy storage railway power regulator, first capacitance voltage of each half-bridge converter unit in the energy storage railway power regulator, and second capacitance voltage, actual current of an energy storage battery and actual charge state of the energy storage battery of each energy storage half-bridge converter unit in the energy storage railway power regulator;

the first processing module 242 is configured to perform current compensation processing on the load current of each phase, and calculate to obtain a first modulation signal for controlling the ac current;

a second processing module 243, configured to perform loop current control processing based on the compensation current of each phase, the first capacitor voltage, and the second capacitor voltage, and calculate to obtain a second modulation signal for loop current control;

the third processing module 244 is configured to perform cell capacitor voltage balancing control based on the first capacitor voltage, the second capacitor voltage, and the actual current of the energy storage battery, perform direct current control based on the actual current of the energy storage battery and the actual state of charge of the energy storage battery, and calculate to obtain a third modulation signal for cell control;

a control signal generating module 245, configured to generate a second control signal of the half-bridge converter unit and a first control signal of an energy storage unit in the energy storage half-bridge converter unit according to the first modulation signal, the second modulation signal, and the third modulation signal.

The control device applied to the energy storage railway power regulator has the same beneficial effects as the control method applied to the energy storage railway power regulator in the embodiment.

Fig. 25 is a schematic diagram of a terminal device according to an embodiment of the present invention. As shown in fig. 25, the terminal device 250 of this embodiment includes: a processor 251, a memory 252 and a computer program 253 stored in said memory 252 and executable on said processor 251, for example a control program applied to an energy storage railway power conditioner. The processor 251 executes the computer program 403 to implement the steps in the above-mentioned control method embodiment applied to the energy storage railway power conditioner, such as the steps 101 to 105 shown in fig. 4, and the processor 251 executes the computer program 403 to implement the functions of the modules in the above-mentioned device embodiments, such as the modules 241 to 245 shown in fig. 24.

Illustratively, the computer program 253 can be divided into one or more program modules, which are stored in the memory 252 and executed by the processor 251 to carry out the invention. The one or more program modules may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution process of the computer program 253 in the control device or terminal device 250 applied to the energy storage railway power conditioner. For example, the computer program 253 may be divided into an obtaining module 241, a first processing module 242, a second processing module 243, a third processing module 244 and a control signal generating module 245, and specific functions of the modules are shown in fig. 24, which is not described herein again.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.